1. Field of the Invention
The present invention relates to a resist composition suitable for lithography and the like acting by high-energy radiation such as far ultraviolet ray (including excimer laser and the like), electron beam, X ray or radiation light.
2. Prior Art
Recently, formation of sub-micron patterns is required because of enhanced integration of integrated circuits. Particularly, lithography using excimer laser from krypton fluoride (KrF) or argon fluoride (ArF) is drawing attention since it enables production of 64 M to 1 G DRAM. As the resist suitable for such excimer laser lithography process, so-called chemical amplification type resist utilizing chemical amplification effect is being adopted. With the chemical amplification type resist, acids generated from an acid generator in parts irradiated with radioactive ray are diffused by the post exposure bake (hereinafter, sometimes abbreviated as PEB), and the solubility of the irradiated parts in an alkali developer is changed by a reaction using the acid as a catalyst, and thereby positive or negative patterns are obtained.
The chemical amplification type positive resist comprises resin which itself is insoluble or poorly soluble in an alkali aqueous solution but becomes soluble in an alkali aqueous solution by the action of an acid, and an acid generator. In general, as the resin which itself is insoluble or poorly soluble in an alkali aqueous solution but becomes soluble in an alkali aqueous solution by the action of an acid, poly(p-hydroxystyrene) protected with acetal group is used. However, when the ratio of the acetal protective group to the resin is increased for enhancing the resolution of the resist, the resolution of dense patterns (dense resolution) increases, while the resolution of isolated patterns (isolated resolution) deteriorates, and when the ratio of the acetal protective group to the resin is decreased for enhancing the isolated resolution, the dense resolution deteriorates, and solubility in an alkali developer increases and membrane remaining ratio decreases, and the like. Therefore, it has been industrially extremely difficult to increase basic abilities such as resolution, particularly isolated resolution and the like by controlling the ratio of the above-mentioned acetal protective group, without lowering membrane remaining ratio.
An object of the present invention is to provide a chemical amplification type positive resist composition which can enhance basic abilities such as sensitivity, resolution, particularly isolated resolution and the like, without lowering membrane remaining ratio.
(0005)
The present inventors have found that the object of the present invention is accomplished by using specific resins in combination as the resin components of a chemical amplification type positive resist composition.
(0006)
Namely, the present invention relates to the followings.
 less than 1 greater than  A chemical amplification type positive resist composition comprising (A) resin having a phenol skeleton wherein the phenol skeleton has protective group which can be dissociated by the action of an acid, the phenol skeleton itself is insoluble or poorly soluble in an alkali aqueous solution and the phenol skeleton becomes soluble in an alkali aqueous solution after dissociation of the protective group (hereinafter referred to xe2x80x9cComponent (A)xe2x80x9d), (B) resin obtained by protecting a part of hydroxyl group in poly(p-hydroxystyrene) with pivaloyl group (hereinafter referred to xe2x80x9cComponent (B)xe2x80x9d) and (C) an acid generator (hereinafter referred to xe2x80x9cComponent (C)xe2x80x9d).
 less than 2 greater than  The chemical amplification type positive resist composition according to  less than 1 greater than , wherein the content of Component (A), Component (B) and Component (C) is 50 to 89.9%, 10 to 50% and 0.1 to 20% by weight respectively, based on the total solid content in the resist composition.
 less than 3 greater than  The chemical amplification type positive resist composition according to  less than 1 greater than  or  less than 2 greater than , wherein the protective group in Component (A) is acetal group.
 less than 4 greater than  The chemical amplification type positive resist composition according to  less than 1 greater than  or  less than 2 greater than , wherein the protective group in Component (A) is 1-ethoxyethyl group.
 less than 5 greater than  The chemical amplification type positive resist composition according to any one of  less than 1 greater than  to  less than 4 greater than , which further comprises an acid proliferating agent in addition to Component (A), Component (B) and Component (C).
 less than 6 greater than  The chemical amplification type positive resist composition according to  less than 5 greater than  wherein the content of the acid proliferating agent is 0.01 to 20% by weight, based on the total solid content in the resist composition.
 less than 7 greater than  The chemical amplification type positive resist composition according to any one of  less than 1 greater than  to  less than 6 greater than , which further comprises a nitrogen-containing basic organic compound in addition to Component (A), Component (B) and Component (C).
 less than 8 greater than  The chemical amplification type positive resist composition according to  less than 7 greater than  wherein the content of the nitrogen-containing basic organic compound is 0.01 to 10% by weight, based on the total solid content in the resist composition.
In the resist composition of the present invention, one of the resin components is Component (A).
The examples of Component (A) can be those obtained by introducing protective group which can be dissociated by the action of an acid into resin having a phenol skeleton. Examples of the resin having a phenol skeleton include poly(p-hydroxystyrene).
Such groups having an ability to suppress dissolution into an alkali developer but unstable to an acid can be various known protective groups. Examples thereof include tert-butyl; groups in which quaternary carbon is bonded to oxygen atom such as tert-butoxycarbonyl, tert-butoxycarbonylmethyl, and the like; acetal type groups such as tetrahydro-2-pyranyl, tetrahydro-2-furyl, 1-ethoxyethyl, 1-(2-methylpropoxy)ethyl, 1-(2-methoxyethoxy)ethyl, 1-(2-acetoxyethoxy)ethyl, 1-[2-(1-adamantyloxy)ethoxy]ethyl, 1-[2-(1-adamantanecarbonyloxy)ethoxy]ethyl, and the like; residues of non-aromatic cyclic compounds such as 3-oxocyclohexyl, 4-methyltetrahydro-2-pyron-4-yl (derived from mevalonic lactone), and the like, and these groups will be substituted for hydrogen atom of phenolic hydroxyl group. These protective groups can be introduced into alkali-soluble resin having phenolic hydroxyl group by a known protective group introduction reaction. The above-mentioned resin can be obtained also by copolymerization using unsaturated compound having such group as one monomer.
In the resist composition of the present invention, other one of the resin components is Component (B).
Specifically, Component (B) is preferably resin obtained by protecting 10 to 60 mol % of hydroxyl group in poly(p-hydroxystyrene) with pivaloyl group.
Component (C), another component of the positive resist composition, is that which is decomposed to generate an acid by allowing radioactive ray such as light and electron beam to act on the acid generator itself or a resist composition containing the acid generator. The acid generated from the acid generator acts on the above-mentioned resin, to dissociate acid-labile group present in the resin. Such acid generators include, for example, onium salt compounds, s-triazine-based organic halogen compounds, sulfone compounds, sulfonate compounds and the like.
Specific examples of the acid generators include the following compounds.
Diphenyliodonium trifluoromethanesulfonate,
4-methoxyphenylphenyliodinium hexafluoroantimonate,
4-methoxyphenylphenyliodinium trifluoromethanesulfonate,
bis(4-tert-butylphenyl)iodonium tetrafluoroborate
bis(4-tert-butylphenyl)iodonium perfluorobutanesulfonate,
bis(4-tert-butylphenyl)iodonium hexafluorophosphate,
bis(4-tert-butylphenyl)iodonium hexafluoroantimonate
bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate,
bis(4-tert-butylphenyl)iodonium camphorsulfonate,
triphenylsulfonium hexafluorophosphate,
triphenylsulfonium hexafluoroantimonate,
triphenylsulfonium trifluoromethanesulfonate,
triphenylsulfonium perfluorobutanesulfonate,
triphenylsulfonium perfluorooctanesulfonate,
tri(4-methylphenyl)sulfonium trifluoromethanesulfonate,
tri(4-methylphenyl)sulfonium perfluorobutanesulfonate,
tri(4-methylphenyl)sulfonium perfluorooctanesulfonate,
4-methylphenyldiphenylsulfonium perfluorobutanesulfonate,
4-methoxyphenyldiphenylsulfonium hexafluoroantimonate,
4-methoxyphenyldiphenylsulfonium trifluoromethanesulfonate,
p-tolyldiphenylsulfonium trifluoromethanesulfonate,
p-tolyldiphenylsulfonium perfluorobutanesulfonate,
p-tolyldiphenylsulfonium perfluorooctanesulfonate,
2,4,6-trimethylphenyldiphenylsulfonium trifluoromethanesulfonate,
4-tert-butylphenyldiphenylsulfonium trifluoromethanesulfonate,
4-phenylthiophenyldiphenylsulfonium hexafluorophosphate,
4-phenylthiophenyldiphenylsulfonium hexafluoroantimonate,
1-(2-naphtholylmethyl)thiolanium hexafluoroantimonate,
1-(2-naphtholylmethyl)thiolanium trifluoromethanesulfonate,
4-hydroxy-1-naphthyldimethylsulfonium hexafluoroantimonate,
4-hydroxy-1-naphthyldimethylsulfonium trifluoromethanesulfonate,
cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,
cyclohexylmethyl(2-oxocyclohexyl)sulfonium perfluorobutanesulfonate,
cyclohexylmethyl(2-oxycyclohexyl)sulfonium perfluorootcanesulfonate,
2-methyl-4,6-bis(trichloromethyl)-1,3,5-triazine,
2,4,6-tris(trichloromethyl)-1,3,5-triazine
2-phenyl-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-chlorophenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-methoxy-1-naphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(benzo[d][1,3]dioxolan-5-yl)-4,6-bis(trichloromeythyl)-1,3,5-triazine,
2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(3,4,5-trimethoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(3,4-dimethoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(2,4-dimethoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine
2-(2-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-butoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-pentyloxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
1-benzoyl-1-phenylmethyl p-toluenesulfonate (generally called xe2x80x9cbenzoin tosalatexe2x80x9d),
2-benzoyl-2-hydroxy-2-phenylethyl p-toluenesulfonate (generally called xcex1-methylolbenzoin tosylate),
1,2,3-benzen-tri-yl tris(methanesulfonate),
2,6-dinitrobenzyl p-toluenesulfonate,
2-nitrobenzyl p-toluenesulfonate,
4-nitrobenzyl p-toluenesulfonate,
diphenyl disulfone,
di-p-tolyl disulfone
bis(phenylsulfonyl)diazomethane,
bis(4-chlorophenylsulfonyl)diazomethane,
bis(p-tolylsulfonyl)diazomethane,
bis(4-tert-butylphenylsulfonyl)diazomethane,
bis(2,4-xylylsulfonyl)diazomethane,
bis(cyclohexylsulfonyl)diazomethane,
(benzoyl)(phenylsulfonyl)diazomethane,
N-(phenylsulfonyloxy)succinimide,
N-(trifluoromethylsulfonyloxy)succinimide,
N-(trifluoromethylsulfonyloxy)phthalimide,
N-(trifluoromethylsulfonyloxy)-5-norbornene-2,3-dicarboxyimide,
N-(trifluoromethylsulfonyloxy)naphthalimide,
N-(10-camphorsulfonyloxy)naphthalimide,
(5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenlyl)acetonitrile,
(5-(4-methylphenyl)sulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile,
(5-butylsulflonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile,
(5-n-octylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile,
(5-(2,4,6-trimethylphenyl)sulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile,
(5-(2,4,6-triisopropylphenyl)sulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile,
(5-(4-dodecylphenyl)sulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile,
(5-(2-naphtyl)sulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile,
(5-benzylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile,
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(methanesulfonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(benzenesulfonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(p-toluenesulfonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(camphorsulfonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(triisopropyobenzenesulfonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(pentafluorobenzenesulfonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(trifluoromethanesulfonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(perfluorobutanesulfonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(perfluorooctanesulfonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis{trifluoro-N-[(perfluoromethyl)sulfonyl]-1-methanesulfonamidate},
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis{perfluoro-N-[(perfluoroethyl)sulfonyl]-1-ethanesulfonamidate},
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis{perfluoro-N-[(perfluorobutyl)sulfonyl]-1-butanesulfonamidate},
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis{trifluoro-N-[(perfluorobutyl)sulfonyl]-1-methanesulfonamidate},
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(tetrafluoroborate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(hexafluoroarsenate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(hexafluoroantimonate),
(oxydi-4,1-phenylene)bisdiphenylsulfonium bis(hexafluorophosphate),
(oxydi-4,1-phenylene)bisdi(4-tert-butylphenyl)sulfonium bis(trifluoromethanesulfonate),
(oxydi-4,1-phenylene)bisdi(4-tert-butylphenyl)sulfonium bis(perfluorobutanesulfonate),
(oxydi-4,1-phenylene)bisdi(p-tolyl)sulfonium bis(trifluoromethanesulfonate),
triphenylsulfonium (adamantan-1-ylmethyl)oxycarbonyldifluoromethanesulfonate, and the like.
As roughness of pattern profile is improved, the present positive resist composition preferably further comprise an acid proliferating agent in addition to Component (A), Component (B) and Component (C). Specific example of the acid proliferating agent include the following compound: 
wherein R1 and R2 each independently represent alkyl having 1 to 15 carbon atoms; alkyl in which at least three hydrogen atoms is sustituted by fluorine atom and having 1 to 8 carbon atoms; or aryl having 6 to 10 carbon atoms.
In addition, performance deterioration due to the deactivation of an acid associated with leaving after exposure can be reduced by adding basic compounds, particularly nitrogen-containing basic organic compounds. Specific examples of such nitrogen-containing basic organic compounds include amines represented by the following formulae: 
In the formulae, R12, R13 and R14 each independently represent hydrogen, alkyl, cycloalkyl or aryl. The alkyl preferably has about 1 to 6 carbon atoms, the cycloalkyl preferably has about 5 to 10 carbon atoms, and the aryl preferably has about 6 to 10 carbon atoms. Furthermore, at least one hydrogen on the alkyl, cycloalkyl or aryl may each independently be substituted with hydroxyl group, amino group, or alkoxy group having 1 to 6 carbon atoms. At least one hydrogen on the amino group each independently may be substituted with alkyl group having 1 to 4 carbon atoms.
R14, R15 and R16 each independently represent hydrogen, alkyl, cycloalkyl, aryl or alkoxy. The alkyl preferably has about 1 to 6 carbon atoms, the cycloalkyl preferably has about 5 to 10 carbon atoms, the aryl preferably has about 6 to 10 carbon atoms, and the alkoxy preferably has about 1 to 6 carbon atoms. Furthermore, at least one hydrogen on the alkyl, cycloalkyl, aryl or alkoxy each independently may be substituted with hydroxyl group, amino group, or alkoxy group having 1 to 6 carbon atoms. At least one hydrogen on the amino group may be substituted with alkyl group having 1 to 4 carbon atoms.
R17 represents alkyl or cycloalkyl. The alkyl preferably has about 1 to 6 carbon atoms, and the cycloalkyl preferably has about 5 to 10 carbon atoms. Furthermore, at least one hydrogen on the alkyl or cycloalkyl may each independently be substituted with hydroxyl group, amino group, or alkoxy group having 1 to 6 carbon atoms. At least one hydrogen on the amino group may be substituted with alkyl group having 1 to 4 carbon atoms
However, none of R12, R13, R17 and R18 in the compound represented by the above formula [3] is hydrogen.
A represents alkylene, carbonyl, imino, sulfide or disulfide. The alkylene preferably has about 2 to 6 carbon atoms.
Moreover, among R12-R18, in regard to those which can be straight-chained or branched, either of these may be permitted.
R19, R20 and R21 each independently represent hydrogen, alkyl having 1 to 6 carbon atoms, aminoalkyl having 1 to 6 carbon atoms, hydroxyalkyl having 1 to 6 carbon atoms or substituted or unsubstituted aryl having 6 to 20 carbon atoms, or R19 and R20 bond to form alicyclic hydrocarbon ring together with adjacent carbon atom.
Examples of such compounds include hexylamine, heptylamine, octylamine, nonylamine, decylamine, aniline, 2-, 3- or 4-methylaniline, 4-nitroaniline, 1- or 2-naphtylamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4xe2x80x2-diamino-1,2-diphenylethane, 4,4xe2x80x2-diamino-3,3xe2x80x2-dimethyldiphenylmethane, 4,4xe2x80x2-diamino-3,3xe2x80x2-diethyidiphenylmethane, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, N-methylaniline, piperidine, diphenylamine, triethylamine, trimethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine, methyldinonylamine, methyldidecylamine, ethyldibutylamine, ethydipentylamine, ethyldihexylamine, ethydlheptylamine, ethyldioctylamine, ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine, tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine, N,N-dimethylaniline, 2,6-isopropylaniline, imidazole, pyridine, 4-methylpyridine, 4-methyimidazole, bipyridine, 2,2xe2x80x2-dipyridylamine, di-2-pyridyl ketone, 1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane, 1,3-di(4-pyridyl)propane, 1,2-bis(2-pyridyl)ethylene, 1,2-bis(4-pyridyl)ethylene, 1,2-bis(2-pyridyloxy)ethane, 4,4xe2x80x2-dipyridyl sulfide, 4,4xe2x80x2-dipyridyl disulfide, 1,2-bis(4-pyridyl)ethylene, 2,2xe2x80x2-dipicolylamine, 3,3xe2x80x2-dipicolylamine, tetramethylammonium hydroxide, tetrisopropylammonium hydroxide, tetrabutylammonium hydroxide, tetra-n-hexylammonium hydroxide, tetra-n-octylammonium hydroxide, phenyltrimethylammonium hydroxide, 3-trifluoromethylphenyltrimethylammonium hydroxide, (2-hydroxyethyl)trimethylammonium hydroxide (so-called xe2x80x9cchollinexe2x80x9d), N-methylpyrrolidone, dimethylimidazole, and the like.
Furthermore, hindered amine compounds having piperidine skeleton as disclosed in JP-A-H11-52575 can be used as quencher.
In the present positive resist composition, the content of Component (A), Component (B) and Component (C) is preferably 50 to 89.9% by weight, 10 to 50% by weight, and 0.1 to 20% by weight, respectively, based on the content, of total solid components in the present positive resist composition.
In resin components of the present positive resist composition, the ratio of P:Q is preferably 1:6 to 1:1, wherein P is total molar amount of the structural units having protective group which can be dissociated by the action of an acid into alkali-soluble resin and Q is the total molar amount of the structural units having phenolic hydroxyl group which itself make resin alkali-soluble.
When the acid proliferating agent is contained in the present positive resist composition, the content of the acid proliferating agent is usually 0.01 to 20% by weight also based on the content of total solid components in the present positive resist composition.
When the basic organic compound is used as a quencher in the present positive resist composition, it is preferred that the content of the basic organic compound in the composition is usually 0.01 to 10% by weight based on the content of total solid components in the present positive resist composition.
The present positive resist composition may also contain various additives such as sensitizers, dissolution inhibitors, resins other than the above resin, surfactants, stabilizers, and dyes as long as, the effect of the present invention is not obstructed.
The present resist composition generally becomes a liquid resist composition under the circumstances in which each of the above-described components is dissolved in a solvent. The liquid resist composition is applied on a substrate such as a silicon wafer according to a usual procedure such as spin coating.
Any solvent may be used as long as they dissolve each component, show suitable drying speed, and give a uniform and smooth film after evaporation of the solvent. Solvents generally used in this field can be used as the solvent.
Examples thereof include glycol ether esters such as ethylcellosolve acetate, methylcellosolve acetate, propylene glycol monomethyl ether acetate and the like; esters such as ethyl lactate, butyl acetate, amyl acetate, ethyl pyruvate and the like; ketones such as acetone, methyl isobutyl ketone, 2-heptanone, cylohexanone and the like; cyclic esters such as xcex3-butyrolactone and the like; alcohols such as 3-methoxybutanol and the like. These solvents can be used each alone or in combination of two or more.
The resist film applied on a substrate, and dried is subjected to an exposure treatment for patterning. Then, after a heat-treatment for promoting a deprotecting reaction (hereinafter referred to xe2x80x98PEBxe2x80x99), development by an alkali developer is conducted. The alkali developer used herein can be various kinds of aqueous alkaline solutions used in this art. In general, aqueous solution of tetramethylammonium hydroxide or (2-hydroxyethyl)trimethylammonium hydroxide (generally referred to as colline) is often used.
Embodiments of the present invention were described above, however, the embodiments of the present invention disclosed above are only examples and the scope of the present invention is not limited to these embodiments. The scope of the present invention is defined by the claims, further, includes equivalent meanings to the claims and any variations in the claims.
The present invention will be further illustrated by examples. However, the present invention is not limited to them at all.
In the examples, % and parts showing content and use amount are by weight unless otherwise stated. Weight-average molecular weight (Mw) and degree of polydispersion (Mw/Mn) are values measured by gel permeation chromatography using polystyrene as a standard.